三角形ABC,a=12cm,b=15cm,c=18cm,各个边上高之比

三角形ABC的面积=S,各个边上高Ha,Hb,Hc
S=Ha*a/2=Hb*b/2=Hc*c/2
Ha*a=Hb*b=Hc*c=2S
12Ha=15Hb=18Hc=2S
Ha=2S/12
Hb=2S/15
Hc=2S/18
Ha:Hb:Hc=(2S/12):(2S/15):(2S/18)=15:12:10